A thermodynamic modeling of the Cu–Pd system

The phase equilibria and thermodynamic properties of the Cu–Pd system are optimized using the CALPHAD (CALculation of PHAse Diagram) technique. In the present work, the liquid and face-centered cubic (fcc) solution phases are modeled with the substitutional solution model. A two-sublattice model (Cu,Pd)0.75(Cu,Pd)0.25 is applied to describe the ordered Cu3Pd phase, the one-dimensional long-period superlattice (1D-LPS) and two-dimensional long-period superlattice (2D-LPS) structures, in order to cope with the order–disorder transition between three intermetallic compounds (Cu3Pd, 1D-LPS and 2D-LPS) and fcc solution (A1) in the Cu–Pd system. A two-sublattice model (Cu, Pd)(Cu, Pd) is used to describe the homogeneity range of CuPd phase. A set of self-consistent thermodynamic parameters is obtained and the calculated phase diagram and thermodynamic properties are presented and compared with the experimental data.